Meet the water bear
0.5 mmtypical length, about the size of a period
8stubby legs with tiny claws
1,300+known species
1773first named "little water bear"
Look in damp moss with a cheap microscope and you'll probably find some.
The tun trick
- Water starts to disappearThe puddle or moss dries out
- The tardigrade curls into a "tun"Legs pulled in, body shriveled
- Life nearly stopsMetabolism drops to almost nothing
- Add water and it wakes upSometimes after years
Built-in protection
Special proteins turn to a glass-like gel that shields cells while dried out.
What they've survived
Outer space
Exposed to vacuum and radiation in 2007, some lived
Deep cold
Near absolute zero, briefly, in the lab
Crushing pressure
Several times deeper than the ocean floor
Radiation
Hundreds of times what would kill a person
Remember
The toughest animal on Earth may be living in the moss on your roof.
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Answer key
- What is another name for a tardigrade?Water bearIt was named "little water bear" in 1773.
- How many legs does a tardigrade have?8Eight stubby legs with tiny claws.
- What is a "tun"?The dried, curled-up survival stateIn the tun state, metabolism nearly stops until water returns.
- In 2007, some tardigrades survived:Exposure to outer spaceSome survived vacuum and radiation outside a spacecraft.
- Where are you likely to find tardigrades?In damp moss almost anywhereMoss and puddles are common homes.